Method of cooking oil bearing vegetable seeds and nuts



Patented Feb. 24, 1953 METHOD OF COOKING OIL BEARING VEGETABLE SEEDS ANDNUTS John W. Dunning, Lakewood, Ohio, assignor to The V. D. AndersonCompany, Cleveland, Ohio, a corporation of Ohio No Drawing. ApplicationMay 10, 1950, Serial No. 161,268

3 Claims. 1

This invention relates in general to the art of extracting oil fromvegetable seeds and nuts such as flax seed, soy beans, caster beans,peanuts, cottonseed and the like. The invention more particularlyrelates to a novel and improved process for cooking material of thenature above indicated whereby to secure the maximum quantity of oil atthe highest quality, and a meal relatively free of toxic ingredients andof the highest nutritive value. The cooking process of my inventionoccurs prior to the customary mechanical expressing step or solventextraction step, and may most advantageously be effected prior to thecombined expression and extraction process disclosed in my copendingapplication for United States Letters Patent, Serial Number 63,223,filed December 2, 1948, for Oil Extraction Process.

As i at present known to those skilled in the art of deriving oil fromvegetable materials of the type above characterized, it is customary tosubject the oil bearing material to a preliminary treatment involvingthe application of relatively elevated temperatures for a fairlyextended period of time, as well as the regulation of the aqueouscontent of the material. In the best practice so far developed theinitial moisture content is limited to a maximum value of about 11%, andthe oil bearing material, with the initial moisture controlled asindicated, is cooked to a final temperature of 240 F. to 270 F. and to afinal moisture content of '3 to over a period of 50 to 120 minutes.

As will later appear, one phase of my invention involves the discoverythat if the best results are to be achieved in oil and meal production,(1) the above moisture content is too low, (2) the evaporation ofmoisture is deleterious, (3) the above temperature is far too high; and(4) the above time at temperature is much too long.

Vegetable seeds and meats consist primarily of oil, proteinaceousmaterial, and fiber. Vegetable seeds and meats also contain many minorconstituents, some of which, for example the phospholipids, as well asthe albumin proteinaceous material, are in the fluid state, and, if theyremain fiuid, are extracted with the oil. It is undesirable tocontaminate the oil with the nonoil fluid fractions of the seeds ormeats and one primary purpose of cooking vegetable seeds or meats is tochange the physical state of the protein'fraction and the phospholipidsso that they become less fluid, and remain with the fiber while the oilis being expressed or extracted.

' Vegetable oils from soy beans, cottonseed, flax- Ill seed and thelike, according to method of the present art, just after extraction areclear after the final filtration step. However, after standing for ashort period they begin to cloud up, and a sediment begins to settle. insome 0113 sedimentation may take place slowly. By a refining process theoil may be cleared, and the sediment settled, but there is an 011 lossin this refining step. This oil loss, from prime seed, as experienced inprior art practice, was sometimes as high as 7 to 12% when analyzed bythe regular method. By the methods of cooking as disclosed hereinbelowthe sedimentary or proteinaceous and phosphatidic material is largelyrendered insoluble so that it remains with the meal of the seed or meatand is not removed in any appreciable quantity with the 011. As aresult, the refining loss of oils prepared in accordance with thepresent invention is distinctly lower than in oils produced heretoforein the art. By my improved process the 011 loss does not exceed about 3to 5 percent. This of course, offers an improved economy to the oilextraction process.

In addition to the more or less fiuid constituents of vegetable seedsand nuts which adversely aifect oil quality according to practices ofthe prior art, certain seeds and nuts contain toxic ingredients whichmay appear in the product oil or more commonly in the extracted meal. Anexample of these toxic factors are the toxic ingredients in cottonseedassociated with the gossypol of cottonseed meats. Cottonseed mealsproduced according to practices of the prior art may contain an amountof gossypol as high as 0.4%. It is common knowledge that such meals havea limited market because of this gossypol content. Although these mealsfind an outlet in cattle feeds, such meal have limited usage in chickenand swine feeds. According to the methods of this invention such toxicingredients of vegetable seeds and meats are detoxified. Cottonseedmeals, for example, when produced according to the methods of thisinvention, contain as low as 0.03% gossypol, This detoxification ofcottonseed meal, for example, provides potential markets for the mealwhich were formerly closed to it.

Many vegetable seed and nut meals are purchased today solely on thephysical appearance and texture of the meal. However, the trend is topurchase these meals on a nutritive basis. In rationalizing this factor,it is common knowledge that a boiled egg is more nutritious than an eggfried at very high temperature. The boiled egg provides a sprongy,fibrous, absorptive protein structure on which the digestive juices mayreadily act. On the other hand, the brown horny protein structure of ahigh temperature fried egg is not spongy and absorptive and offersconsiderable resistance to the digestive juices. Similarly, a vegetableseed or nut meal, prepared according to the methods of this invention ofcocking at relatively low temperatures for a short time in the presenceof relatively high moisture content provides a spon y, fibrous,absorptive protein structure. This structure not only readily gives upits oil, but also may be readily acted upon by the digestive juicesofthe animal. On the other hand, vegetable seeds or nuts cookedaccording to the practices of the prior art,

wherein they may be cooked attemperatures as high as 250 to 270 F. forlong periods of time, and at relatively low moisture content, provide amore horny protein structure.

Briefly summarizing theobjects of the present invention, I aim toprovide a simple and effective cooking treatment applicable to oil"bearingvegetable seeds and nuts prior to extraction of oil therefrom,the results ofthe-treatment' being to achieve maximum quantity'and'highest quality of the oil; to provide a mealof' highest nutritive valueconsistent with quality; to prevent contamination of oil' by fluidizedproteinaceous material; to denaturize or coagulate the soluble proteinfractions so that they are not expressed with theoil; to provide aporous and fibrous protein material; to precipitate the phosphatidicmaterials in the solid mass whereby they are'not expressed or'extractedwith the oilyto' prevent oil loss in refining by reducing sedimentation;to free the meal from toxiciactors' suclr as those usually associatedwith gossypol fractions; to enable the oil' to be extracted atlower-pressures, and to achieve higheroil yields event, at such lowerpressures.

I have discovered that the foregoing'objects are accomplished firstby'subjecting the'oil bear ing materialtoa cooking process'in which thesignificant steps-vary to-a material extent from the practices of theprior art.

cent. As a result of extensive tests I have determinedthat the practicesof the-prior artproduced a'hard, horny, dry material-from which oil isextracted only with; relativedifficulty. In theory this hard materialgives goodbody for mechanical expression, but actually the hard cellularstructure yields the'oil only grudgingly and ineificiently. Whileachieve good results with a moisture-content range of about 12 to 20 percent; I normally recommend and use a moisture content of about 12 to 14per cent. The mannerof achieving this will be disclosed in a specificexample hereinafter.

Whereas in prior. art practice the oil bearing material was heated toarelatively high temperature; for. example 240'F. to 270 F., forarelatively extended; period of time, for instance 80 to 120 minutes; Ihave'foundthat the hereinbefore detailed objects and advantages oithepresent in.- vention are achieved by heating at a temperature of between190 F. and 215 F. for a relatively short time, for example between 7 to20 minutes. For hydraulic or screw press extraction of oil, thetime maybe between 12 and 20 minutes, and I prefer a treatment not exceeding 15minutes. If the-oil is to be extracted by a combined process involvingmechanical pressure followed by solvent extraction, in the novel mannerdisclosed Whereas the priorart maintained the-moisture-content at lessthan 12'per cent during-the cooking step, I maintain the moisturecontent at between 12 andZdperin my aforesaid copending application, thecooking time can be shortened to a period between 7 and 15 minutes.

In the prior art, it has been necessary to comminute the raw materialsinto particle size of .003 to .010 in order to obtain rapid and uniformheat transfer during the cooking stage. This comminution was preferablydone in a multistage rolling mill although single stage rolling mills,as well as hammer mills have been used. Although according to thepractice of this invention it is necessary to comminute the raw material before cooking, one of the advantages of the methods of thisinvention lies in the fact that the thickness of the particles toundergo the cooking process is less critical than in the prior artbecause of the moisture and temperature conditions of the cookingprocess. The particle thickness for the methods of this invention neednot be controlled closer than within the limits of .005to .025thickness.

For example, according to the prior art of cooking cottonseed meats, a5-high stand rolling mill having a 20" x 60" bottom roll was recom--mended to comminute the meatsfrom to-l10. tons of cottonseed per 24 hourday. By the use. of the methods ofthis invention the same size' rollingmill can comminute the meats front 210 tons of 'cottonseedper 24 hourday.

As previously mentioned, the cooking process,

according to method of this invention, are conducted at a temperature ofl90 to-2l5 F. fora" period of time from 7 to 20 minutes at amoisturecontent ranging from 12 to 20%.-

sel. is approximately 12%, the ratio of water to steam added to the rawmaterial enterin the cooking vessel may be varied according to themoisture content of the raw material. ample, if the raw materialcontains approximately 7% moisture a mixture of steam andwater in theratio of approximately 2 to 1 may be employed. This particular mixtureof steamand water provides sufficient moisture'for wetting of the rawmaterial, and at the same time, it also. provides heat for raising thetemperatureof the raw material to approximately If the moisture. of theraw material, is" higher than 7%, for example 9 to 10%, theratio.

heat and moisturehot only permit the desirable shortening of the cookingtime butit also. prevents-localized overheating ofthe vegetableiseeds.and nuts in contact. with. the steam. jacketed.

surf aces.-

In following the methodsv of this invention it. is necessarythatno realevaporationoimoisturefrom the seed or. meats-takeplace duringthe,

cooking process.- The, prior artitor. screw. press operation states thatvegetable seeds and cuts at The-attaining of this moisture-content maybe accom plished by the addition of steam and/or Water" to the mass ofmeats entering the cooking ves-- Since the minimum moisture to beattained For ex- I The useof" llVE. steam and water as theprimarysource. of"

a moisture content of, for example, 11% shall be cooked to a finaltemperature of 245 F. and a final moisture of 3%. It has been discoveredthat such directions even at lower temperatures and higher initialmoistures do not give the desirable results of this invention ifevaporation of moisture takes place during the cooking stage. Thiseffect is illustrated in the table hereinbelow.

In order that the method of cooking, as disclosed in the presentspecification, may be carried out in the most uniform manner, I preferto comminute the oil bearing material or meat, after delinting and/orhulling depending upon the specific vegetable seed and before cooking,in the usual single or multistage rolling mill, or by a hammer or anattrition mill. This enables the heat transfer to be more rapid anduniform. In one specific mode of operation cottonseed meats were rolledto .015" flakes and continuously charged into a steam jacketed cookerprovided with water and steam sparging lines. The moisture content ofthese meats was 7.15%. The ratio of water to steam added to the meatswas about one part of water to seven parts of steam. The steam waterspray was discharged into the cooker at the feeding end in such volumeas to maintain the moisture content constant at about 13 percent. Thetime the material remained in the cooker was about 15 minutes.Immediately upon entry the sparged steam raised the temperature of thecharge to about 180 F. Sufiicient steam was admitted to the steam jacketof the treatin vessel to raise the temperature of the charge to 210 F.The cooked material was continuously withdrawn from the cooker at ameasured temperature of 210 F. and a moisture content of 13%. It wasthen dried to a moisture content of about 5 percent, a value here foundto be suitable for full oil extraction by means of the mechanical screwpress. The refining loss of the resultant oil was between 3% and 5%, ascompared with about to 11% for oil resulting from prior art cookingtechnique. The resultant meal contained only negligible quantities oftoxic ingredients. Actually the amount of gossypol in the meal was0.04%.

While the moisture content before screw press extraction after prior artcooking should be reduced to approximately 3%, I have found that aftercooking in accordance with my present invention the moisture content canbe as high as 5% to 5.5%, for complete full press extraction. Thisprovides a more ductile cake from the screw press, permitting longerwear of press parts. As a matter of fact, if the material is to betreated in accordance with the teachings of the invention disclosed inmy above acknowledged copending application, the moisture content may beas high as 7% whereas in prior practice 5% was regarded as thepermissible maximum.

In the practice taught in said copending application, vegetable seedhigh in oil content is first mechanically expressed to reduce the oilcontent to about one-fourth the total protein content in the seed cake.The cake is then comminuted and flaked to a flake thickness from .005 to.02 inch in thickness, and, after moisture and temperature factors aresuitably regulated, the flakes are solvent extracted. In said priorinventive process the advantageous result achieved thereby was aductile, nonfriable flake which lent itself readily to solventextraction without undue development of fines in the solvent extractionprocess.

I have found that extremely satisfactory overall results are achieved byfirst cooking the seed meats in accordance with the teachings of thepresent specification, and then subjecting the cooked seed to theprocess outlined in the copending application. A vegetable seed cookedas herein described, and with a cooking time of 7 to 15 minutes, yieldsultimate flake from the press cake which are tough and ductile, and donot develop appreciable fines in the subsequent handling and extractionsteps. This particular advantage results in lower labor and operationcosts and a higher yield of oil.

As one specific example of the use of the present invention combinedwith the practice taught in the said copending application, the meatsderived from cottonseed at the rate of 210 tons per day were comminutedto particles of .020" thickness. These comminuted particles were cookedat 13.5% moisture at 205 F. for a period of 12 minutes in a continuouslyoperated steam jacketed cooker. The meats contained an original moisturecontent of 9.5%. A steamwater sparge in the rates of 8 to 1 was employedto give a moisture content of 13.5% and an initial temperature of F. Thecooked meats were then dried to '7 moisture content in a horizontalsteam jacketed drier at a maximum temperature of 220 F. The oil producedby the method taught in the said copending application had a refiningloss of only 3.8%. The product meal had a gossypol content of 0.03%.

The data in the table obtained from commercial scale operations oncottonseed further illustrate the advantages of the methods of this Afurther advantage realized by the methods of cooking, as abovedescribed, regards the relative ease with which the oil may be expressedfrom the cooked vegetable seed or nut meats as compared to the priorart. When vegetable seeds or nut meats are cooked according to themethods of this invention the fibrous, spongy nature of the proteinconstituents are readily compressed and these same constituents readilygive up their oil. According to the methods of the prior art, whereinthe oil is expressed from a vegetable seed by means of a mechanicalscrew press the residual oil in the finish meal may range from 4 to 5%.When the methods, according to the present invention are utilized, theresidual oil in the meal from the same type of mechanical screw pressoperation may be as low as 3.0 to 3.5%, and when the methods of thepresent invention are combined with those of my prior copendingapplication the residual oil may be materially less than 0.5%.

What I claim is:

1. A method of treating oil bearing seed and nut meats prior toextraction of the oil therefrom, comprising raising the moisture contentof the meats to a value between 12 per cent and 20 per cent, and cookingthe meats for a period between 7 and 20 minutes at a temperature ofbetween-7 and 20.3minutes.while:maintaining:the

moisture content: thus gained by the meats without appreciableevaporation. of: moisture taking, places. and: thereafter. discharging.the meats from theivessel.

3;. In: preparation. for; the; process of extracting: oil= frommut: andseed meats wherein the; material. is; subjected: to. the successive.steps. of mechanically. expressing. some ofthe oil;,while'= retaining:int the-z materiali after; the expressing step: a. natural. oilf.content; of about. one-fourth. the total protein content as existingatthe termination of: the. expressing step, eomminuting. the. resultingpress cake, flaking; the; comminutedi cake, anclfinally solventextracting theiresidual" oil from. the flakes, thenovel preparatorysteps of raising the moisturecontentf of the. meats to a. valuein-excessof.12.per.cent and cooking the meatsfor. from 7 to 15 minutesat a temperature between190 F..and 2l5? Fl JOHN W; DUNNINGL.

REFERENCES CITED.-

The following. references are of record in the file of this patent:

UNITED. STATESv PATE1 'I'I$i.-

Number Name Date 312,674. Thornton "Feb. 24,-.1885'1 8431983 WoodwardFeb; 12,1907;

1,164,383 Nelaei .Dec. 14,1915 928,241 Barton' Sept; 26:, 1933:

OTHER REFERENCES Alton: E. Bailey: text.Cottonseed. and Cotton seedProducts, published 1948 by Interscience Publishers, Inc.,. New York,pages. 615- to 627.

1. A METHOD OF TREATING OIL BEARING SEED AND NUT MEATS PRIOR TOEXTRACTION OF THE OIL THEREFROM, COMPRISING RAISING THE MOISTURE CONTENTOF THE MEATS TO A VALUE BETWEEN 12 PER CENT AND 20 PER CENT, AND COOKINGTHE MEATS FOR A PERIOD BETWEEN 7 AND 20 MINUTES AT A TEMPERATURE OFBETWEEN 190* F. AND 215* F. UNDER SUCH CONDITIONS THAT EVAPORATION DOESNOT REDUCE THE MOISTURE IN THE SEED OR NUT MEATS BELOW 12 PER CENT.